Filter

- When a filter resolves an identifier through a DOM reference, it records
  the source. In other words, when 'priority' is resolved to 'H', the source
  reference ('priority') is stored in the variant. This is because different
  data attributes behave differently when compared.

src/Filter.cpp

@@ -48,6 +48,7 @@ bool domSource (const std::string& identifier, Variant& value)
   if (stringValue != identifier)
   {
     value = Variant (stringValue);
+    value.source (identifier);
     return true;
   }